The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Buswell light rail report light on insight

Former West Australian treasurer Troy Buswell's light rail report from a taxpayer-funded trip across Europe is so paltry it could have been compiled in his office, the state opposition says.

Mr Buswell came away from the trip to Europe and China with six key findings about light rail as he planned a network for Perth.

Mr Buswell, now a backbencher after quitting cabinet following a car crash controversy in March, visited Switzerland, Germany and France in August and September last year to study light rail systems.

Before making the trip, Mr Buswell had said non-essential government travel would be temporarily banned and instructed the public service to tighten its belt amid spiralling state debt.

And in December, the state government shelved its MAX light rail project due to WA's ailing finances.

A 20-page report since submitted by Mr Buswell on the trip contained six insights about light rail, with the fact it could be a "very effective, embedded and highly valued component" of a public transport system split over two bullet points.

Mr Buswell also used two bullet points to report that trams could operate effectively in confined urban settings at sensible speeds and with clear community awareness of the operation.

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His other points were that right of way for light rail in congested parts of a city was important and that a tram system could be delivered effectively via a public-private partnership, particularly in a greenfields environment.

Opposition transport spokesman Ken Travers said Mr Buswell could have compiled the light rail report from his Perth office and saved taxpayers money.

In China, Mr Buswell met with state-owned conglomerate CITIC and Industrial Bank of China about investment opportunities including Perth Stadium and the long-awaited Oakajee port.

And with his then-fisheries minister hat on, he also held several meetings about artificial reefs, shark barriers and seafood trade.

The total cost of the trip is expected to be tabled in parliament in coming weeks.

On his return to parliament as the Member for Vasse last week, Mr Buswell told reporters it was "entirely appropriate" for ministers to travel for work.

Mr Travers said on Sunday Mr Buswell's report, which used swathes of general information from websites, was light on insights.

"I don't think there was anything in that report that added value to what we do," he told AAP.

He believed Mr Buswell already knew funding for the MAX project was questionable before he got on the plane.

While Mr Buswell provided a brief report to parliament one month after the trip, the full report took eight months to be tabled, said Mr Travers, who admitted he'd once returned a late travel report too.